Construction of Removable Partial Denture - Semmelweis...
Transcript of Construction of Removable Partial Denture - Semmelweis...
Peter Hermann Department of Prosthodontics
Semmelweis University
Construction of Removable Partial
Denture
Treatment options for edentulous spaces
• Fixed prosthodontics
(crowns/bridges)
• Removable prosthodontics (dentures)• Complete dentures
• Transitional denture (Dentures designed in such a
was as to facilitate addition of prosthetic teeth as and
when remainingteeth need to be extracted)• RPD
• Implant retained /supported
prosthodontics
• No prosthetic treatment
Large diversity of treatmentcomplexity
• Number of teeth to be replaced
• Health of residual dentition
• Health of patient
• Patient requirements
• Patient expectations
• Dentist competence
• Laboratory competence & liaison
• TIME!
• MONEY!
Need and demand
‘How many teeth must be
lost before a patient
seeks prosthetic
replacement?’
In a UK survey people were asked, 'If you had several missing teeth
at the back would you prefer to have an RPD or manage without?’
Shortened Dental ArchNo prosthetic treatment may be an appropriate option
• THIS DOES NOT MEAN NO RESTORATIVE orPREVENTATIVE TREATMENT
• The provision of a distal extensionRPD may not contribute anysignificant functional benefits
• A minimum of 8-10 occluding pairsof anterior teeth
• Must be periodontally sound• Strictly speaking upper and lower
secondpremolar to second premolar• Replacement of missing posterior
teeth should be driveny demand and function, not by habit
Removable partial denture
• an appliance which restores a partial
loss of natural teeth and associated
tissues
• it can be removed from the mouth and
replaced by the patient
Saddle• “That part of the denture that rests
on the oral mucosa”
or alternatively
“The space(s) to be filled by thedenture”
• Replaces the lost of thealveolar tissues and carriesarteficial teeth (obligatoryfunction)
• Can take part in support and retention (optional function)
• Types: 1. bounded
2. free end
Support classification of partail denturesSupport: resistance to vertical components of masticatory
force in a direction toward the basal seat
• Dental
• Dento- mucosal
• Muco- dental
• Mucosal
Retention• Retention: the resistance to
movement of a removable partial
denture from its supporting tissues
• Clasp
• Precision attachment
• Telescopic retainers
• The minor connectors(coloured red) join the smallcomponents, such as restsand clasps, to the saddles orto the major connector.
• The major connector(coloured black) links thesaddles and thus unifies thestructure of the denture.
Connectors: minor or major
• Connects the two sides of the denture(the saddles) together, provides therigid unit of the dental appliance(obligatory function)
• Can take part in the support and retention (optional function)
• Upper arch:
- butterfly (lateral edentulous areas)
- horseshoe (anterior edentulous area)
- fenestrated (decreasing the size of the
baseplate)
- sceletonized (fully tooth-supported)
Connector
Lower arch:
• Lingual bar: most widely used
The lingual bar, like the sublingual bar, should be placed as lowas the functional depth of the lingual sulcus will allow.
• Sublingual barThe sublingual bar differs from the lingual bar in that itsdimensions are determined by a specialized masterimpression techniquethat accurately records the functionaldepth and width of the lingualsulcus
• dental bar: where the clinical crowns are longenough
• 'Kennedy Bar' or continuous clasp: consists of a dental bar, combined with a lingualbar
Guidelines fordesigning the connector
part• the protection of the tissues of the
marginal periodontium must be carriedout
• Reduction
• The connector part must be rigid, thepossibility of reduction depends on thetype of the support
• With straight contour we provide theproper cleaning of the removablepartial denture, and it is more comfortable for the patient (speech)
• The material of the baseplate is metal, except in the cases of mucosal and dental, and mucosalsupport
• Provides thetooth support(obligatoryfuncion)
• Can take part in avioding tilting(optionalfunction)
Support
Procedures in the office and in thelaboratory
• Medical and dental history
• extra-and intraoral examination
• Xray analysis
• classify the dental condition (Fábián and Fejérdy)
• Primary impresion taking
• Treatment planning
The removable partial denture equation
• Initial step in determining if prosthetic
treatment is indicated must always be the assessmentof:
• The patient’s wishes and concerns
• The relevant dental and medical history
• The results of the extra-oral and intra-oralexaminations
• Oral hygiene habits and status
• The essential oral functions of appearance, mastication and speech.
Benefits
• Appearance
• Speech
• Mastication
• Maintaining the health of the masticatory system:
—preventing undesirabletooth movement
—improving distribution of occlusal load
Satisfactory outcome depends upon the clinician, the dental technician and the patient.
Study casts
• Stock try
• Elastic impression
(silicone) material
• One stage/ two
stage impression
technique
Impression 1.
Impression 2.• Materials used for primary
impression taking:• alginate• silicones
Taken by a stock tray !
• After pouring out the primary impressionin the laboratory, we get the primary cast
• On the primary cast we outline theborders of the special tray
• secondary impression withspecial tray (silicones)
• On the secondarycast at the dentaloffice we design theremovable partialdenture, outline thesaddle areas, occlusal rests and the retainers
• The secondary castis the mastercast(made of stone orprecise die stone)
• With the duplicaton of the
mastercast we get the
working cast for making the
wax pattern and investing
• Materials used for
duplicating the
mastercast:• duplicating gels
• silicones
• On the surface of the
workingcast the dental
technician makes the wax
pattern from prefabricated
wax elements
After sprueing the
working cast is
ready for investing
• Investing with flask
• Investment materials used for
cobalt-chromium alloys:
• Phosphate bonded
• Silica bonded
• Gypsum bonded
• Investing is carried out by
vibration.
• Deflasking
• Finishing of the
ready metal frame
• (sandblasting,
trimming, polishing)
• At the dental office we check the ready frameworks and
determine the jaw relationship with wax occlusal rim and
determine the shade
• At the laboratory they set up the teeth
• After setting up the teeth we try in
the trial denture at the office
• Check up the occlusion,
articulation,
• Check shade
Processing
Insertion• Check the
occlusion!
• Correction
• Recall
Combined fixed-removable prosthodontic restoration
• Single crowns on 34 and 2 unit splint on 44,45 and RPD:• precision attachment /friction screw/ on tooth 34 • Ball attachment attached to the teeth 44 & 45 • E-clasp placed on tooth 37• chrome cobalt lingual bar together with all stress distributors
and E-clasps will be cast in one piece
Attachment prosthesis
claspless restorations
•Intra coronal connections
•Extra coronal connections
•Inter coronal connections
industrial manufactured
attachments:primary and
secondary part (male and
female) guarantees the
anchoring of the prosthesis to
the remaining dentition
Circumferential shoulder and interlock
the stress distribution arms of the cobalt framework lock to it
• chamfered parallel milling with a cervical and/or occlusalshoulder
• allows a proportionate force distribution onto theparodontium
• serves as a tool for the path of the insertion• offers stabilization against horizontal and vertical forces• supports the rigid connection to the attachment.
Complete wax up of the crowns•always done in an articulator
•anatomical form of the crown and the
stress distributor of the chrome cobalt
frame, guarantee a biodynamic balance
Set up of the artificial teeth•always done in an articulator
•availability of space and how to attach the
construction elements onto the chrome
cobalt frame.
•modelling of the tissue and the later
acrylic saddle areas allows an judgement
of the overall aesthetic appearance of the
prothesis.
Investing
Casting
Deflasking
Blasting
Finishing
•Ceramic material is
veneered (sintered) onto a
metal frame of FPD in several
firing processes
• Fixed restoration tried in
• Taking impression of fixed
restoration
Dr Csilla Erdei: case report
•duplicating part been placed onto
the ball anchor to produce the investment
or refractory models
•undercuts blocked out with special
wax so the model can be easily removed
from the duplicating material.
•preparation wax is used on the
enclosed and free end saddles, to create
space for the acrylic
• duplicating gels are reversible
thermoplastic materials
•After the cooling process has finished the
master model will be removed from the gel
and the investment material will be
poured into the gel form
• investment or refractory
model is produced for the
wax up of the framework
• sprues serve as a feed line
for the melt into the actual
cast object
• Investing the modellation
• Casting
• Deflasking
• Sandblasting
• Polishing
• duplicating part for
casting/ female retentive
part is fixed and locked in
• Try in procedure of finished CrCo-
framework (with fixed prosthodontics
together)
• Bite registration• Set up artificial teeth
• Trial Denture
• Acrylic finishing
• Cementation of fixed-
removable
prosthodontic
restoration together
• Recall!
Thank you for yourattention!